1. Field of the Invention
The invention is directed to an automatic differential lock which is actuated when the wheels on one side of the differential slip in relation to wheels on the other side of the differential more than a programmed amount.
2. Description of the Prior Art
Off road vehicles may be provided with differentials that can be selectively locked and unlocked. Typically the differential lock is controlled by a solenoid operated differential lock control valve that is controlled by a single manually operated foot pedal. To actuate the differential lock the operator must continually depress the foot pedal. Because the differential lock may interfere with steering the differential lock may be disengaged when the vehicle is steered either by application of left or right brakes, or the steering system itself. See U.S. Pat. Nos. 4,523,494 and 4,570,509.
In another differential lock control system, the left and right brakes and the speed of the vehicle can disengage an applied differential lock. The differential lock can be reengaged in response to signals from a steering sensor, a wheel slippage sensor and a draft load sensor. See U.S. Pat. No. 4,549,448.